Light emitting diode with quantum barrier doping

Abstract

A light emitting diode including a substrate, a p-type and n-type semiconductor layers, an active layer, an interlayer, an electron barrier layer, a first and a second electrodes are provided. The n-type semiconductor layer is disposed on the sapphire substrate. The active layer has an active region with a defect density greater than or equal to 2×10 7 /cm 2 . The active layer is disposed between the n-type and p-type semiconductor layers. The wavelength of light emitted by the active layer is λ, and 222 nm≦λ≦405 nm. The active layer includes i quantum barrier layers and (i−1) quantum wells, each quantum well is disposed between any two quantum barrier layers, and i≧2. N-type dopant is doped in at least k layers of the i quantum barrier layers, wherein k is a natural number and k≧1, when i even, k≧i/2, and when i is odd, k≧(i−1)/2.

What is claimed is: 
     
       1. A light emitting diode, comprising:
 a sapphire substrate; 
 a n-type semiconductor layer disposed on the sapphire substrate; 
 an active layer having a defect density DD, wherein DD≧2×10 7 /cm 2 , the active layer is disposed on a portion of the n-type semiconductor layer, and a wavelength λ of light emitted by the active layer is λ≦365 nm, the active layer comprising i quantum barrier layers and (i−1) quantum wells, each of the quantum wells is disposed between any two quantum barrier layers, and is a natural number greater than or equal to 2, wherein a n-type dopant is doped in at least k layers of the quantum barrier layers, and the other (i−k) quantum barrier layers are undoped, k being a natural number greater than or equal to 1, when i is an even number, k≧i/2, and when is an odd number, k≧(i−1)/2; 
 a p-type semiconductor layer disposed on the active layer; and 
 a first electrode and a second electrode, wherein the first electrode is disposed on a portion of the n-type semiconductor layer, and the second electrode is disposed on a portion of the p-type semiconductor layer, 
 wherein the doping concentration of the each of the k quantum barrier layers counting sequentially from the n-type to the p-type semiconductor layer side are C 1 , C 2 , . . . C k , where C k <C k−1 . 
 
     
     
       2. The light emitting diode as claimed in  claim 1 , wherein the k quantum barrier layers doped with the n-type dopant are located nearest to the n-type semiconductor layer. 
     
     
       3. The light emitting diode as claimed in  claim 1 , wherein a material of the quantum barrier layers comprises Al x In y Ga 1-x-y N, wherein 0≦x≦1, 0≦y≦0.3, and x+y≦1. 
     
     
       4. The light emitting diode as claimed in  claim 1 , wherein a thickness of each of the quantum barrier layers is between 5 nm to 15 nm. 
     
     
       5. The light emitting diode as claimed in  claim 3 , wherein a material of the quantum wells comprises Al m In n Ga 1-m-n N, wherein 0≦m<1, 0≦n≦0.5, m+n≦1, x>m, and n ≧y. 
     
     
       6. The light emitting diode as claimed in  claim 1 , wherein a respective thickness of each of the quantum barrier layers, counting from the p-type semiconductor layer, is T 1 , T 2 ,T 3  . . . , and T i  in sequence, and T 1 is greater than T 2 and T 3 . 
     
     
       7. A light emitting diode, comprising:
 a sapphire substrate; 
 a n-type semiconductor layer disposed on the sapphire substrate; 
 an active layer having a defect density DD, wherein DD≧2×10 7 /cm 2 , the active layer is disposed on a portion of the n-type semiconductor layer, and a wavelength λ of light emitted by the active layer is λ≦365 nm, the active layer comprising i quantum barrier layers and (i−1) quantum wells, each of the quantum wells is disposed between any two quantum barrier layers, and i is a natural number greater than or equal to 2, wherein a n-type dopant is doped in at least k layers of the quantum barrier layers, and the other (i−k) quantum barrier layers are undoped, k being a natural number greater than or equal to 1, when i is an even number, k≧i/2, and when i is an odd number, k≧(i−1)/2; 
 a p-type semiconductor layer disposed on the active layer, a doping concentration of the quantum barrier layer in the k quantum barrier layers nearest to the p-type semiconductor layer being less than the doping concentration of the other quantum barrier layers in the k quantum barrier layers; and 
 a first electrode and a second electrode, wherein the first electrode is disposed on a portion of the n-type semiconductor layer, and the second electrode is disposed on a portion of the p-type semiconductor layer. 
 
     
     
       8. The light emitting diode as claimed in  claim 7 , wherein the k quantum barrier layers doped with the n-type dopant are located nearest to the n-type semiconductor layer. 
     
     
       9. The light emitting diode as claimed in  claim 8 , wherein the doping concentration of the k quantum barrier layers is at least 5×10 17 /cm 3 . 
     
     
       10. The light emitting diode as claimed in  claim 7 , wherein a material of the quantum barrier layers comprises Al x In y Ga 1-x-y N, wherein 0≦x≦1, 0≦y≦0.3, and x+y≦1. 
     
     
       11. The light emitting diode as claimed in  claim 7 , wherein a thickness of each of the quantum barrier layers is between 5 nm to 15 nm. 
     
     
       12. The light emitting diode as claimed in  claim 10 , wherein a material of the quantum wells comprises Al m In n Ga 1-m-n N, wherein 0≦m<1, 0≦n≦0.5, m+n≦1, x>m, and n≧y. 
     
     
       13. The light emitting diode as claimed in  claim 7 , wherein a respective thickness of each of the quantum barrier layers, counting from the p-type semiconductor layer, is T 1 , T 2 , T 3  . . . , and T i  in sequence, and T 1  is greater than T 2  and T 3 . 
     
     
       14. A light emitting diode, comprising:
 a sapphire substrate; 
 a n-type semiconductor layer disposed on the sapphire substrate; 
 an active layer having a defect density DD, wherein DD≧2×10 7 /cm 2 , the active layer is disposed on a portion of the n-type semiconductor layer, and a wavelength λ of light emitted by the active layer is λ≦365 nm, the active layer comprising i quantum barrier layers and (i−1) quantum wells, each of the quantum wells is disposed between any two quantum barrier layers, and i is a natural number greater than or equal to 2, wherein a n-type dopant is doped in at least k layers of the quantum barrier layers, and the other (i−k) quantum barrier layers are undoped, k being a natural number greater than or equal to 1, when i is an even number, k≧i/2, when is an odd number, k ≧(i−1)/2, and a doping concentration of the k quantum barrier layers is from 5×10 17 /cm 3  to 1×10 19 /cm 3 ; 
 a p-type semiconductor layer disposed on the active layer; and 
 a first electrode and a second electrode, wherein the first electrode is disposed on a portion of the n-type semiconductor layer, and the second electrode is disposed on a portion of the p-type semiconductor layer, 
 wherein the doping concentration of the each of the k quantum barrier layers counting sequentially from the n-type to the p-type semiconductor layer side are C 1 , C 2 , . . . C k , where C k <C k −1 . 
 
     
     
       15. The light emitting diode as claimed in  claim 14 , wherein the k quantum barrier layers doped with the n-type dopant are located nearest to the n-type semiconductor layer. 
     
     
       16. The light emitting diode as claimed in  claim 14 , wherein the doping concentration of the quantum barrier layer in the k quantum barrier layers nearest to the p-type semiconductor layer is less than or equal to the doping concentration of the other quantum barrier layers in the k quantum barrier layers. 
     
     
       17. The light emitting diode as claimed in  claim 14 , wherein a thickness of each of the quantum barrier layers is between 5 nm to 15 nm. 
     
     
       18. The light emitting diode as claimed in  claim 14 , wherein a respective thickness of each of the quantum barrier layers, counting from the p-type semiconductor layer, is T 1 , T 2 , T 3  . . . , and T i  in sequence, and T 1 is greater than T 2 and T 3 .